This invention relates to a landmass simulator, and, more particularly, to a real-time landmass or terrain simulator that provides stationary and three-dimensional detail so that it may be used effectively for radar training especially in the use of a high resolution radar.
One source of terrain descriptions is the Defense Mapping Agency which digitizes topographic regions by outlining areas (such as industrial, residential and forestial) having a similar composition and makes available the resulting data base. These areal, i.e. having an area, features are typically defined by polygons with a predominant composition and specified height. One problem with trying to simulate these areal features is that on prior displays they appear like large, solid polygons, potentially several square miles in area, and thus seem artificial.
A radar landmass or terrain simulator is described and claimed in U.S. Pat. No. 4,168,582--Heidrich, assigned to the instant assignee. Although the images produced in accordance with the teachings of Heidrich satisfy training criteria for certain classes of radar, generally of lower resolution, they are not especially well suited for displaying stationary real-time fine detail that is desired for comprehensive training on high-resolution radars. In order to provide images useful for training on a high-resolution radar, it is necessary that the detail remain stationary, i.e. does not shift position in the landmass representation as the simulated radar position or sweep changes. In addition, it would be desirable to be able to present three dimensional features that more nearly represent images to be expected from processing actual radar return signals. Further, it would be desirable to incorporate high detail source images, such as obtained from aerial photographs and/or satellite sensors, for specific world areas, like an airport or city, along with the topographic data base of the surrounding area for producing high fidelity simulated radar images of the specific world areas.
It may be possible to introduce desired data descriptors into the data base by using an off-line operation. Problems with such schemes include the necessity to perform pre-processing (i.e. storage of the desired data in the data base so that the features they define are recalled in the appropriate position of the landmass) and the increased bulk storage size, e.g. disk or magnetic tape, required for storing the additional pre-processed information.
Accordingly, it is an object of the present invention to provide a landmass simulator for generating fine detailed images for a high-resolution radar.
Another object is to present images exhibiting three-dimensional features for high-resolution radar.
A further object is to present images for high resolution radar without need to preprocess data.
Still another object is to avoid increasing the size of the bulk storage medium required for the topographic data base.
Yet another object is to present images wherein the detail remains stationary regardless of the orientation of the radar.
An additional object is to present images wherein high resolution detail of specific areals, like an airport, may be readily incorporated along with detail from a topographic data base of the surrounding area.